Numerous studies suggest that a network of interrelated brain areas are involved in attentional processes and working memory. Areas of the brain implicated in attention and working memory are key regions in which structural abnormalities and functional deficits have been identified in schizophrenia and been found to be sexually dimorphic in normals. However, few studies have specifically focused on elucidating sex differences in attention/working memory in schizophrenia. Further, there is some evidence that sex differences in cognitive processing differ by sensory modality, i.e., auditory versus visual cognitive stimuli. The investigator's and others' work have shown that schizophrenic men and women may be at differential risks for expressing different forms of the illness. Thus, an understanding of sex differences in attention and working memory may be important for understanding the heterogeneity of cognitive deficits in schizophrenia. This Small Grant proposes a two-year pilot study to use fMRl to identity sex differences in the neural processing of verbal and nonverbal sustained attention and working memory in two sensory modalities, i.e., auditory versus visual. The investigator will develop cognitive paradigms for use in the fMRI environment to specifically test hypotheses focused on sex differences. Nonverbal auditory and verbal and nonverbal visual sustained attention/working memory paradigms will be developed, matched for degree of difficulty, with the investigator's already-developed and tested verbal auditory sustained attention paradigm. The sample will consist of 20 DSM-IV schizophrenics, half men/half women, and 20 normal controls individually matched, within sex, on age, ethnicity, parental socioeconomic status (SES), Wide Range Achievement Test (WRAT) reading, and right-handedness. Subjects will be randomly selected from the investigator's larger sample of well characterized outpatient chronic schizophrenics and matched normal controls, who have already received a battery of clinical and cognitive tests, and some of whom have received structural imaging. Based on the investigator's and others' previous studies, the investigator predicts significant sex differences in: activations of the inferior and dorsolateral prefrontal cortex, posterior parietal cortex, and in the anterior cingulate gyrus; in lateralization of hemispheric activations from verbal versus nonverbal cognitive stimuli; and in visual versus auditory stimuli. Findings will contribute to an understanding of sex differences in the nature of schizophrenia, and how, or whether, they deviate from sex differences in the normal brain.